Monolithic and cellular polycarbonates of different thicknesses are painted and transparent. The nomenclature of polymeric materials of this type is diverse. The consumer appreciated the high technical characteristics and widely uses polycarbonate for greenhouses.
In order to determine which polycarbonate is best for a greenhouse, it is necessary to carefully study the properties of both types of transparent plastics. With the same chemical composition, they have a different structure and significantly differ in their technical characteristics. The choice of coating material for greenhouses is carried out taking into account the requirements for the design of such structures.
Content:
- Which polycarbonate is better for a greenhouse - cellular or monolithic
- What thickness polycarbonate is better to use for a greenhouse
- What color polycarbonate is better to choose for a greenhouse
- Polycarbonate with and without UV protection
- Comparative characteristics of popular manufacturers of polycarbonate
Which polycarbonate is better for a greenhouse - cellular or monolithic
The main function of the greenhouse is to provide the optimal temperature and humidity conditions necessary for growing crops in significant quantities. To solve this problem, facilities are required that cover rather large areas. To erect this is possible only when using materials with a low specific gravity, otherwise a strong and, as a consequence, heavy frame will be required.
It is cellular polycarbonate that has a hollow structure that best meets these requirements. Compared to monolithic, this material has a significantly lower specific gravity with the same sheet thickness. So, one square meter of a 10-mm cell polycarbonate panel is more than an order of magnitude lighter than a whole sheet of the same chemical composition. In addition, cellular polycarbonate, due to its hollow structure, has lower thermal conductivity. This circumstance is decisive in deciding the choice of coating for greenhouses.
Sheets of monolithic polycarbonate.
Sheets of cellular polycarbonate.
So, we decided that a greenhouse needs cellular polycarbonate, but which one is better from the wide range of products on the market? This coating is selected based on a complex of various properties and characteristics, the list of which includes the following:
- mechanical strength;
- resistance to changing environmental conditions;
- thermal conductivity;
- light transmission;
- availability of protection against hard ultraviolet radiation.
Cellular polycarbonate has high parameters for all the above items, information on the technical characteristics of the panels is presented in the table:
| Polycarbonate Characteristic | Units rev. | Options | ||||
|---|---|---|---|---|---|---|
| Panel thickness | mm | 4 | 6 | 8 | 10 | 16 |
| Specific gravity | kg / m2 | 0,8 | 1,3 | 1,5 | 1,7 | 2,5 |
| Sheet length and width | m | 2,10×6,00 | ||||
| Minimum bending radius | m | 0,8 | 1,3 | 1,5 | 1,7 | 2,5 |
| Light transmittance | % | 82 | 78 | 75 | 72 | 62 |
| Thermal conductivity | W / m2 ° C | 3,6 | 3,4 | 3,0 | 2,7 | 2,0 |
| Operating temperature | ° C | -40 - +130 | ||||
| Max. linear expansion | mm / m | 3 | ||||
The characteristics of cellular polycarbonate depend on two main factors: the quality of the feedstock and strict adherence to the material production technology. The manufacture of panels is carried out by extrusion on special equipment. Different manufacturers use raw materials with different properties, and their material structure may vary.
The above factors are taken into account when choosing a particular brand of cellular polycarbonate for the construction of a greenhouse. In addition to these parameters, the cost of the panel, which directly depends on the thickness and quality of the sheet, is crucial.Cheap materials, as a rule, are made in violation of technical specifications and they are not able to withstand prolonged use.
What thickness polycarbonate is better to use for a greenhouse
The following factors influence the choice of thickness of cellular polycarbonate for sheltering a greenhouse:
Crate pitch used for greenhouse
The shape and angles of the slopes of the used greenhouse
Snow load and temperature conditions in the region
Type of crops to be cultivated
The customer is often tempted to obtain cost savings and to purchase the thinnest and most inexpensive sheet to cover the greenhouse. This decision will lead to the need to increase the load-bearing elements of the frame, to compensate for the insufficient strength of the panel, which during operation is subjected to significant wind and snow load. In addition, cheap material often does not match the declared thickness, which also does not contribute to improving its technical characteristics.
You should not go to the other extreme and use polycarbonate of maximum thickness for the construction of the greenhouse. A four-layer thick panel with a complex structure of stiffeners, which significantly reduces light transmission. In addition, a larger specific gravity of the sheet will also require strengthening the supporting structure of the frame.
Practice shows that the optimal thickness of polycarbonate for coating greenhouses is from 4 to 10 mm. It is important to consider that when choosing panels, you should pay attention not only to the declared technical characteristics, but also to the quality of the material. The latter should be confirmed by the presence of a certificate of compliance of the material with the requirements of the national standard issued by an accredited laboratory for a specific batch of products.
The recommended step of the crate for a cellular polycarbonate greenhouse is 700 mm or 1050 mm, this step is equal to half or a third of the sheet width and allows to reduce material consumption.
Dependence of the thickness of the sheet of cellular polycarbonate on the cell size of the crate of the greenhouse with a snow load of 180 kg / sq.m:
When building arched greenhouses, the maximum possible bending radius of the material should also be considered. This indicator also depends on the thickness of the material (see table above), but may vary depending on the manufacturer (see table below).
The angle of the roof slope will also affect the required sheet thickness. But this indicator is relevant only for pitched greenhouses. That is why often in pitched greenhouses the walls are made of polycarbonate 4 mm thick, but the roof is 6-10 mm thick. It is best to use arched or drop-shaped greenhouses in regions with heavy snow load that do not contribute to the accumulation of snow on the roof of the greenhouse.
Snow load in various regions of the Russian Federation.
In regions with moderate snow load, sheets of cellular polycarbonate with a thickness of 4-6 mm are most often used.
The thickness of the material depends on the purpose of the greenhouse. If the future greenhouse is planned to be used for distillation of seedlings, then it is best to take cellular polycarbonate 6 mm thick, but 4 mm will be enough to grow early vegetables.
What color polycarbonate is better to choose for a greenhouse
Manufacturers offer painted and fully transparent polymer panels. When choosing the colors of cellular polycarbonate for the construction of a greenhouse, the consumer should proceed from two considerations. First of all, the coating should ensure maximum light transmission of the panels and the lighting inside the structure should be as close as possible to the natural solar spectrum.
These requirements are met by transparent polycarbonate panels, which have the highest light transmission at about 80%. At the same time, opal color sheets delay and scatter up to 40% of the sun's rays, and fashionable bronze panels completely absorb up to 60% of the radiation. This circumstance will adversely affect the plants, and will impede their normal growth and development.
Among other things, color sheets have selective light transmission. Radiation from that part of the spectrum that is necessary for crops simply does not reach them. This situation cannot contribute to high yields. Experts recommend using transparent panels as a coating, which make the greenhouse as light and warm as possible.
Transparent cellular polycarbonate.
Polycarbonate with and without UV protection
During long-term operation, transparent plastic is exposed to intense sunlight. The ultraviolet part of its spectrum is capable of triggering photoelectric destruction processes, microcracks initially form on the surface. Over time, they grow, which ultimately leads to fragility of the panel and its gradual destruction.
To protect against these processes, a special coating is applied to the outer layer of cellular polycarbonate. The technology of coextrusion with the mutual introduction of materials eliminates the separation of the protective layer from the base. On most types of materials, such a coating is only on one side. To inform the user, a label is placed on the packaging film indicating how to mount the panel.
On certain types of polycarbonates, a photo stabilizing coating is applied on both sides of the sheet. Such panels are used for outdoor advertising structures or sound-absorbing screens, which are installed along major roads near settlements. Their use for the construction of the greenhouse is meaningless, since in this case only one side is exposed to ultraviolet radiation.
Manufacturers also offer polycarbonate, which does not have a light stabilizing layer. Such panels are used exclusively for interior work and are not suitable for greenhouses. Destructive processes will lead to the destruction of the panel after one year of operation. For greenhouses, it is recommended to use high-quality cellular polycarbonate with one-sided UV protection from well-known brands. As a rule, such sheets are glued with a film on which there is a designation on which side there is a protective layer.
Acquisition of inexpensive material produced by a company that does not have a name or does not indicate it is likely to mean a waste of money. Such plastic, as a rule, will not serve the established period and will have to be replaced with a better one in the near future. When choosing cellular polycarbonate for a greenhouse, you should focus on your own financial capabilities and avoid substandard products.
Comparative characteristics of popular manufacturers of polycarbonate
On the Russian market there are many types of transparent plastic made by domestic and foreign manufacturers. Consider the most common brands of cellular polycarbonate, presented by different manufacturers. For the convenience of data analysis, the article will describe two-layer panels with a thickness of 4 mm with stiffeners perpendicular to its surface.
SafPlast Innovative
One of the largest manufacturers of cellular polycarbonate in our country, SafPlast Innovative launches its products under the brand name Novattro. Products of this company are well established among consumers and are in steady demand.
Bayer material science
Another manufacturer, Bayer Material Science, offers consumers polycarbonate under the brand name Makrolon. These products are of the highest quality and have excellent characteristics.
Poligral
The Russian-Israeli company Polygal delivers cellular polycarbonate under the same name to the market. Relatively inexpensive and durable material with a long service life.
Plastilux
The products of the Chinese company “PlastiLux”, the Sunnex trademark, belong to the category of the most affordable materials and are popular with the buyer.
The main characteristics of honeycomb polycarbonate panels with a thickness of 4 mm are listed in the table:
| Specifications | Units rev. | Manufacturer and brand | |||
|---|---|---|---|---|---|
| Safplast Novattro |
Bayer Makrolon |
Polygal | Plastilux Sunnex |
||
| Distance between ribs | mm | 6 | 6 | 5,8 | 5,7 |
| Specific gravity | kg / m 2 | 0,75 | 0,8 | 0,65 | 0,79 |
| Light transmission | % | 84-87 | 81 | 82 | 86 |
| Minimum bending radius | mm | 700 | 750 | 800 | 700 |
| Heat transfer resistance | M2° C / W | 5,8 | 4,6 | 2,56 | 3,9 |
From the information presented, it can be concluded that the claimed characteristics of the material from different manufacturers are approximately at the same level. The practice and study of customer reviews, at one time, who bought a particular type of polycarbonate shows the following:
1. The cheapest panels of the Sunnex trademark serve no more than 3 to 4 years with a declared life of 8 years.
2. Polygal-Vostok cellular polycarbonate ensures that its characteristics remain unchanged for about 10 years, provided that it is installed correctly. At the same time, the material is quite rigid and durable, during the installation process it takes the shape of the frame well.
3. The Novattro panels from the Russian manufacturer SafPlast have proven themselves on the positive side. Reasonable price with a maximum life of at least 8 years.
4. The highest technical specifications for polycarbonate honeycomb brand Makrolon. According to the results of operation in the middle band, the sheet retains its integrity and basic properties for at least 12 years.
In view of the foregoing, it can be safely stated that the products of a Chinese company have the shortest service life, and German panels have the longest.
